A need exists for simple and efficacious delivery of intraluminal therapies. Such therapies range from delivery of anti-mitotic agents to reduce the restenosis following angioplasty, to delivery of angiogenic factors, delivery of therapeutic agents to reduce intravascular thrombus, delivery of therapeutic agents to improve arterial compliance through the structural alteration of intimal and medial calcification, delivery of fluent cross-linkable materials that may be hardened in situ to provide support for a vessel (e.g., as is described in U.S. Pat. No. 5,749,915 to Slepian, the entire contents of which is incorporated herein by reference), or to exclude or reduce the development of a nascent vascular aneurysms. Previously-known methods and apparatus typically involve use of multiple catheters and devices to accomplish such treatments, which adds time, cost and complexity, increased exposure to ionizing radiation and risk of morbidity to previously-known therapeutic procedures. It therefore would be advantageous to provide methods and apparatus that simplify such previously-known procedures, reduce time, cost and complexity, and improve acute procedural success and long-term patient outcomes.
Percutaneous transluminal angioplasty of coronary and peripheral arteries (PTCA and PTA, respectively) are widely accepted as the revascularization procedures of choice in patients with ischemic cardiovascular syndromes (i.e., chronic and acute coronary ischemic syndromes and chronic limb ischemia, including claudication and critical limb ischemia). However, use of these conventional percutaneous treatments has an important limitation: restenosis—the exuberant proliferation of smooth muscle cells that grow to re-occlude the treated vessel segment, causing the reoccurrence of symptoms and necessitating potential reintervention.
Various adjuncts to angioplasty seek to reduce restenosis; these include atherectomy (e.g., extractional, rotational, orbital, laser), bare metal and bare nitinol stents and, more recently, drug eluting stents (DES). The latter technology has been demonstrated to significantly reduce coronary artery restenosis when compared to angioplasty or bare metal stents, however, its use requires chronic administration of adjunct pharmacotherapies to prevent subacute stent thrombosis, the sudden and life threatening clotting of the stent. Unfortunately, not all patients tolerate these essential pharmacotherapies due to impaired tolerance, allergic reactions or contraindication to such drug use (i.e., history of previous bleeding) and/or their associated expense.
In peripheral arteries, the use of bare nitinol stents have been shown to be superior to balloon angioplasty alone and has emerged as the “default” percutaneous strategy for the treatment of chronic limb ischemic syndromes, particularly in complex disease patterns involving the femoropopliteal artery. Despite their common use, nitinol stents present a substantial concern of in-stent restenosis (ISR), the proliferation of smooth muscle cells within the stent leading to occlusion of the stent lumen. ISR poses additional risk to the patient by necessitating additional vessel reintervention to re-establish vessel blood flow.
Currently, there is no established treatment for the vexing problem of ISR, which occurs in about 30%-50% of nitinol stents over a 1-2 year follow-up period, a rate that may increase depending on the patient demographic (i.e., diabetics) and vessel morphology (small vessel diameter, length of diseased vessel treated and the presence of vessel wall calcification). Importantly, there are presently no recognized effective and durable therapies to treat ISR; as such, emerging technologies focus on preventing restenosis through the application of anti-restenotic therapeutic agents into the diseased vessel wall layers via the vessel's luminal surface.
Anti-proliferative drugs (i.e., paclitaxel, sirolimus) retard smooth muscle migration into an area of angioplasty-induced vessel injury and reduce restenosis. Drug delivery catheters have been designed to facilitate the delivery of such therapeutic agents into the vessel wall via its luminal surface. For example, U.S. Pat. No. 5,112,305 to Barath et al. describes a catheter having a single balloon including a multiplicity of protrusions. The protrusions include apertures that enable a drug to be introduced into the balloon and infused through the apertures into the vessel wall. U.S. Pat. No. 5,049,132 to Shaffer et al. and U.S. Pat. No. 6,733,474 to Kusleika each describe a catheter having an impermeable inner balloon and an outer balloon having pores through which a drug may be infused into the vessel wall. U.S. Pat. No. 5,681,281 to Vigil et al. similarly shows a catheter having an impermeable inner balloon and an outer balloon having a multiplicity of apertured protrusions for injecting a drug into a vessel wall. U.S. Pat. No. 5,213,576 to Abiuso et al. describes a catheter having nested balloons with offset apertures, to reduce jetting and provide more uniform distribution of a drug infused into a vessel through the catheter.
All of the previously-known systems described in the foregoing patents have had drawbacks that have prevented commercialization of those designs. For example, catheters having a single apertured balloon, such as described in the above patent to Shaffer et al., cannot provide uniform distribution of a drug or other material around the circumference or along the axis of the vessel due to jetting through the apertures. Catheters with apertured protrusions, such as described in the above patents to Barath et al. and Vigil et al, are difficult to manufacture and are believed to be prone to having the apertures clogged with debris when the balloon is embedded into the plaque lining the vessel wall. Also, the use of excessively high pressures within the balloon to clear the apertured protrusions may lead to excessively non-uniform drug infusion and potential vessel dissection.
On the other hand, in a catheter such as described in Abiuso et al., nested balloons having offset apertures cause the inner balloon to serve as a baffle that reduces jetting through the apertures in the outer balloon, thereby providing a much more uniform infusion through the outer balloon. However, as the Abiuso catheter lacks an inner impermeable balloon to move the drug infusing layers into apposition with the vessel wall, there is the potential for much of the drug to be washed into systemic circulation during deployment of the nested balloons. Moreover, because Abiuso lacks a dilatation balloon, it has no ability to disrupt calcified plaque, and accordingly, must be used with a separate dilatation balloon requiring additional catheter exchanges, contrast and radiation exposure and vessel irritation.
Recent clinical data has identified a variety of atherosclerotic plaque morphologies in coronary and peripheral vessels, which prevent the effective penetration of drug therapies into the various vessel layers. Specifically, the presence of dense fibro-calcific and calcified intimal and medial plaques, are associated with peri-procedural failure (due to vessel recoil and/or vessel wall dissection) and subsequent restenosis as these plaques are effective barriers to the penetration and uptake of therapeutic drugs delivered luminally. As such, the instructions for use (IFU) of many current approved devices and inclusion/exclusion angiographic criteria of on-going regulatory trial designs specifically exclude patients from device treatment with angiographic evidence of severely calcified vessels. Given the large and growing patient population with diabetes and chronic kidney disease and conditions associated with heavy vessel wall calcification, this represents a substantial patient population in which emerging therapies may be ineffective.
In view of the many drawbacks of previously-known systems and methods, it would be desirable to provide apparatus and methods that overcome such drawbacks. In particular, it would be desirable to provide devices suitable for intraluminal therapies, such as intravascular drug infusion systems and methods, which reduce the number of equipment exchanges needed to both disrupt intravascular plaque and to infuse an anti-stenotic agent into a vessel wall to reduce occurrence of restenosis.
It further would be desirable to provide devices and methods suitable for intraluminal therapies, such as intravascular drug infusion systems and methods, that permit a clinician to dilate a vessel to disrupt calcified plaque and then to infuse an anti-mitotic agent into the vessel wall through the disrupted plaque.
It still further would be desirable to provide devices and methods suitable for intraluminal therapies, such as intravascular drug infusion systems and methods, wherein a balloon of the catheter may include a multiplicity of apertures, such that the apertures are resistant to clogging during use of the balloon to dilate the vessel and disrupt the plaque.
Previously known systems also describe the use of various energy sources to deliver energy to fluent material infused into a vessel to pave a vessel or create an in situ stent. Such systems are described, for example, in U.S. Pat. No. 5,662,712 to Pathak et al. and U.S. Pat. No. 5,899,917 to Edwards et al. A drawback of these systems, however, is that each forms a new mechanical structure disposed within the vessel that is separate and distinct from the vessel wall. Because the arteries, and to a lesser extent, the veins, expand and contract during each cardiac cycle due to pressure pulsations, such attempts to form a rigid mechanical support that is not integrated with the vessel wall are inherently problematic.
It therefore further would be desirable to use existing vasculature structure to enhance or perpetuate the anti-mitotic effect of drugs infused via an intravascular route. In particular, it would be desirable to employ application of energy, e.g., such as ultraviolet (UV) light energy, monopolar or bipolar generated radiofrequency (RF) generated heat, or focused or unfocused ultrasonic energy, to potentiate the delivery and effectiveness of anti-mitotic agents when administered from the luminal surface into the media and adventitial layers in the presence of vascular calcification.